The magma starts cooling and crystallizing. The crystallization cause the magma to change composition. This is referred to as magma evolution.
Molton rock that flows from a volcano onto Earths surface is
Lava.
lava
lava
Runoff
Valcano
runoff
it is called lava
it would be lava , magma is in the ground and flows on earths surface and cools to lava
Lava ;D
it flows because if convection currents
It forms rhyolite.